1. Field of the Invention
This invention relates to illuminated display, and more particularly to a display device, which presents 360-degree viewable, 3-dimensional hologram, an optical film holder and transport system for recording the images and a method for making the same.
2. Description of Related Art Including Information Disclosed under Secs. 1.97-1.99
Various types of ornamental illuminated display devices have been provided in the past. Some of these devices have obtained a desired visual effect of changing light patterns by passing light through rotating elements contained within transparent housings located between the viewer and the source of light. Two or more liquids of different colors have been utilized, with air bubbles being passed through the liquids to provide changing colors and patterns. Typical of such devices are those shown in U.S. Pat. No. 3,613,264—Vitka et al, U.S. Pat. No. 3,706,149—Olivieri, and U.S. Pat. No. 3,964,194—Gugeler. For instance, the Gugeler patent describes a changeable color device wherein an illumination source is located within three concentric cylinders formed of a light transmissive material, between pairs of which air is bubbled through a liquid.
Other ornamental illuminated display devices have obtained the desired visual effect of changing light patterns by causing the movement of one or more light transmissive means of varying shapes and colors with respect to the light source. Typical of such devices are those shown in the following U.S. patents: U.S. Pat. No. 2,867,716—Ream U.S. Pat. No. 3,791,058—Mollica U.S. Pat. No. 3,179,791—Mole U.S. Pat. No. 5,065,289—Teng U.S. Pat. No. 3,686,494—Naylor U.S. Pat. No. 5,394,309—Brown
The Ream patent discloses an ornamental display device wherein a bulb is located in a rotating drum which is provided with perforations through which light projects to a clear plastic cylindrical shell. The Mole patent describes an illuminating device wherein three lenses of different colors are mounted in a triangular form on a support, which rotates about a light source. The light passing through the lens also passed through an aperture formed in the spherical housing containing the light source and lens.
The Naylor patent illustrates a lighting apparatus wherein two concentric cylindrical light transmissive members having designs thereon are caused to counter-rotate around a light source. The heat generated by the light source causes air currents to engage blades secured to the cylinders to cause them to rotate. The Mollica patent sets forth a device for providing visual effects including a source of black light located within a rotatable hollow cylindrical translucent element having a pattern thereon subject to fluorescence. The translucent element is surrounded by a cylindrical lens, which is located within a translucent rectangular housing.
U.S. Pat. No. 4,832,424 to McGrew describes cylindrical holograms that are viewable in monochromatic light such as those created by Dr. Tung Jeong. Dr. Jeong describes a single-step process wherein an object is placed inside a cylinder of holographic film and both object and film are illuminated simultaneously by a laser beam diverging from a point on the axis of the cylinder. Light scattering from the object interferes with the light directly illuminating the film and produces an interference pattern on the film. The exposed film is developed to yield a hologram of the object, viewable by rolling the film into a cylinder and illuminating it with monochromatic light from a point on the axis corresponding to the point from which the reference beam diverged. A significant disadvantage of Dr. Jeong's process, which is overcome by the present invention, is that the hologram requires an expensive monochromatic illuminating source, such as filtered mercury are lamp or a laser.
Another prior art cylindrical hologram is the “Cross” hologram, such as is described in U.S. Pat. No. 4,206,956. The Cross hologram is synthesized from a large number of two-dimensional images and is analogous to a lenticular photograph. While the Cross hologram is viewable in white light, it must be manufactured by a complex process requiring expensive precision equipment, and it requires production of a motion picture film under special conditions.
Also in the prior art is a hologram covered by U.S. Pat. No. 3,633,989 to Dr. Steven Benton. Dr. Benton's patent primarily covers a means of producing an information-limited hologram of a subject for the purpose of making a white-light viewable image. The method produces white-light viewable holograms, but will not work for making cylindrical holograms, without cumbersome optical systems for forming and reconstructing holograms in a cylindrical symmetrical arrangement. The method calls for forming a real image of the subject of the hologram and limiting the vertical parallax of the light forming the real image.
Several workers in the field have attempted to copy cylindrical holograms by flattening an original cylindrical hologram, then reconstructing to form a second hologram on a plane parallel to the plane of the flattened original, but at a distance away. An example of such attempts is described in U.S. Pat. No. 4,339,168. One purpose of the attempts was to create a second hologram which formed a cylinder of smaller diameter, but which contained an image of the original size; another purpose was to create a second hologram whose image intersected the plane of the film.
These attempts worked poorly because flattening the cylinder rearranges the wavefront in such a way that the image is severely distorted and has no well-defined location. Haines' two-step method is inherently incapable of compensating for the distortions caused by changing the shapes of the holograms.
Prior to the present invention, there was no known low cost method for creating a white-light viewable hologram such as the multiplexed holograms of cylindrical “Cross” type, described in U.S. Pat. No. 4,206,956 by Stephen P. McGrew. Prior art relating to spatial filtration of wavefronts was described by Dr. Steve Benton as a method for producing white-light viewable holograms wherein a first hologram is constructed at a certain location (the “viewing location”); then a second hologram is formed at the real image position from the real image reconstructed when a long horizontal strip of the first hologram is illuminated by the conjugate to its reference beam.
In Benton's method, restricting the reconstructed portion of the first hologram to a horizontal strip is a form of spatial filtering. Once the first hologram has been made, there is no choice of viewing location. The cylindrical Cross hologram and T. Jeong's cylindrical laser-viewable hologram are prior art cylindrical holograms. The Cross hologram is made in a series of steps including production of a cinema film. Jeong's hologram is made in a single step and is not white-light viewable.
U.S. Pat. No. 5,570,208 discloses a stereoscopic display method, a forming method, and a stereoscopic display apparatus of a hologram for performing a stereoscopic display by forming a hologram of a virtual object or an object which actually exists and, more particularly, to a stereoscopic display method, a forming method, and a stereoscopic display apparatus of a hologram for performing a natural stereoscopic display by using a 2-dimensional image.
A stereoscopic display is a display for enabling a depth or a thickness of a 3-dimensional object to be easily visually understood. Such a stereoscopic display is strongly demanded in a display of a structural object designed by a CAD or the like, a display of a medical image, or the like. On the other hand, a solid image is more impressive as compared with a 2-dimensional display and is also used in a display for amusement in an amusement park, a movie, or the like.
With respect to the stereoscopic displays, in general, various kinds of methods have already been proposed. There is a hologram as means in which an observer can see a solid image without using special glasses. The hologram is a special image in which an object image was recorded by using an interference operation of the light. With regard to a still object, a color hologram having a depth feeling has already been produced. On the other hand, as a method whereby a virtual object having a 3-dimensional structure formed by the CAD or the like is stereoscopically seen, there is a computer graphics (CG). The computer graphics is a technique in which a 2-dimensional image, when an object is seen from a predetermined direction, is calculated and is really expressed in consideration of the reflection or shadow of the light. Since the computer graphics, however, intends to obtain a 2-dimensional image, a stereoscopic feeling is insufficient. It is possible to display, with a stereoscopic feeling, by a holographic stereogram system such that 2-dimensional images, when an object is seen from various directions, are sequentially recorded into stripe-like regions, each having a microwidth in the horizontal direction and a width of screen in the vertical direction, by the holographic exposure on the basis of the 2-dimensional image by the computer graphics.
According to the conventional holographic stereogram, however, a 2-dimensional image is fundamentally seen and the surface at which a focal point of the eyes is located doesn't coincide with the position of the image which is observed by a parallax of both eyes. Therefore, it is hard to see and such a state results in a cause of a fatigue. Particularly, in a case of displaying an image of a deep depth, a burden on the eye increases and such a stereoscopic display is undesirable. The conventional hologram is recorded onto a film-like medium and it takes time to develop the image, so that it is inconvenient as a stereoscopic display system. Further, the display contents cannot be rewritten.